In the related art, a battery pack assembly of a vehicle is usually mounted on a tray, the tray and an enclosure jointly define a cavity used to hold a battery assembly, and various cooling water channels or cooling air channels whose structures are complex are provided in the cavity. This structure requires that the cavity has a relatively large space, and a cooling water channel and a cooling air channel cannot be compatible with each other. Therefore, commonality is not strong. Particularly, for a water cooling structure, wiring of a cooling water channel is complex, and once leakage occurs, the battery assembly is likely to be short-circuited, affecting service life and service safety of the battery pack assembly.